Wheel support apparatus

ABSTRACT

A wheel support apparatus including a hub wheel which includes a hub shaft and is to mount a wheel thereon, a first side surface spline being formed on an end surface of the hub shaft, and a constant velocity joint which includes an outer ring connected to the hub shaft in a torque-transmitting manner, a second side surface spline meshed with the first side surface spline being formed on an end surface of a side wall portion of the outer ring abutting against the end surface of the hub shaft. Each of the first and second side surface splines includes a number of spline teeth and bottom lands defined between the spline teeth. The tooth tops of the spline teeth of one of the two side splines and the bottom lands of the other side spline are formed into a tapering surface inclined relative to a plane perpendicular to a center axis of the hub shaft. The tapering tooth tops contact the corresponding tapering bottom lands so that the hub shaft and the outer ring can be aligned with each other.

The present Application is a Divisional Application of U.S. patentapplication Ser. No. 12/285,361, filed on Oct. 2, 2008, (now U.S. Pat.No. 8,025,579) the disclosure of which is incorporated herein byreference.

The present application claims priority from Japanese Application No.2007-259693, Japanese Application No. 2007-259694, and JapaneseApplication No. 2008-086743, the disclosures of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

This invention relates to a wheel support apparatus in which a hub shaftof a hub wheel for the mounting of a wheel thereon and an outer ring ofa constant velocity joint are connected together in atorque-transmitting manner.

There is known one conventional wheel support apparatus of this type inwhich a hub shaft of a hub wheel and an outer ring of a constantvelocity joint are interconnected by an connecting bolt, and also twoside surface splines are formed respectively on an end surface of thehub shaft of the hub wheel and an end surface of a side wall portion ofthe constant velocity joint which abuts against the end surface of thehub shaft, and the hub wheel and the constant velocity joint areconnected together in a torque-transmitting manner through the two sidesurface splines (see, for example, JP-A-63-184501).

When the two side surface splines formed respectively on the end surfaceof the hub shaft of the hub wheel and the end surface of the side wallportion of the constant velocity joint are meshed with each other,thereby connecting the hub wheel and the constant velocity jointtogether in a torque-transmitting manner as described above, it isfeared that muddy water or the like splashed up by a wheel mayaccidentally intrude into the interior through a clearance between thetwo side surface splines meshed with each other, so that rust maydevelop in the interior.

One conventional wheel support apparatus of the type described isdisclosed, for example, in JP-A-2002-114004.

In this wheel support apparatus, a double row angular contact ballbearing 120 comprising an inner ring 121, an outer ring 130 and balls(rolling elements) 141 and 142 is mounted on an outer peripheral surfaceof a hub shaft 113 of a hub wheel 110 as shown in FIG. 17.

On the other hand, a connecting shaft portion 163 is formed integrallyon and extending from an end surface of a side wall portion 161 of anouter ring 160 of a constant velocity joint 150 to which an end portionof a drive shaft 151 is connected. An internal spline 114 is formed onan inner peripheral surface of a bore of the hub shaft 113 of the hubwheel 110, and an external spline 164 for meshing with the internalspline 114 is formed on an outer peripheral surface of the connectingshaft portion 163.

The connecting shaft portion 163 is inserted and fitted into the bore ofthe hub shaft 113 of the hub wheel 110 while the internal and externalsplines 114 and 164 are brought into meshing engagement with each other,and then a lock nut 166 is fastened onto an male-threaded portion 165projecting from a distal end of the connecting shaft portion 163, and bydoing so, the hub wheel 110 and the constant velocity joint 150 areconnected together in a torque-transmitting manner.

In the wheel support apparatus disclosed in JP-A-2002-114004, forexample, during the travel of a vehicle, a torque of the outer ring 160of the constant velocity joint 150 rotating in the same direction as thedirection of rotation of the drive shaft 151 is transmitted to the hubwheel 110 through the internal and external splines 114 and 164 meshingwith each other, thereby driving the wheel to rotate it.

At this time, a relative slip (slip including a torsion) sometimesdevelops between the end surface of the side wall portion 161 of theouter ring 160 of the constant velocity joint 150 and an end surface(that is, an end surface of a caulked portion 117) of the hub shaft 113of the hub wheel 110, so that an abnormal sound is generated.

In order to prevent the generation of an abnormal sound due to arelative slip between the end surface of the side wall portion 161 ofthe outer ring 160 of the constant velocity joint 150 and the endsurface of the hub shaft 113 of the hub wheel 110, the inventor of thepresent invention has proposed a structure as shown in FIG. 18, in whicha side surface spline 280 is formed on an end surface of a caulkedportion 217 of a hub shaft 213, and a side surface spline 290 is formedon an end surface of a side wall portion 261 of an outer ring 260 of aconstant velocity joint 250 abutting against the end surface of the hubshaft 213, and the two side surface splines 280 and 290 are meshed witheach other to connect the hub shaft 213 of a hub wheel 210 and the outerring 260 of the constant velocity joint 250 together in atorque-transmitting manner.

In the case where the side surface splines 280 and 290 are formedrespectively on the end surface of the caulked portion 217 of the hubshaft 213 and the end surface of the side wall portion 261 of the outerring 260 of the constant velocity joint 260 by forging, each bottom land282, 292 of each of the two side surface splines 280 and 290 is formedinto an inclined surface gradually increasing in depth from itsradially-inner end to its radially-outer end.

Therefore, the meshing engagement of the two side surface splines 280and 290 is limited at the radially-inner portions of the bottom lands282 and 292. As a result, non-contact portions S where the spline teethof the spline 280 and the spline teeth of the spline 290 will notcontact each other develop at the radially-outer end portions of thebottom lands 282 and 292 of the two side surface splines 280 and 290.Therefore, it is thought that a contact pressure and a shear stress oftooth flanks of the spline teeth at the mutually-contacting portions ofthe two side surface splines 280 and 290 increase, so that thedurability may be adversely affected.

Another conventional wheel support bearing apparatus of this type isdisclosed in JP-A-57-178903.

In this conventional wheel support bearing apparatus, in order toconnect a hub wheel 210 and a constant velocity joint 250 together in atorque-transmitting manner as shown in FIG. 19, a side spline (sidesurface spline) 290 is formed on an end surface of a hub shaft 213 ofthe hub wheel 210, and a side spline (side surface spline) 280 is formedon an end surface of an end wall portion 261 of the outer ring 260 ofthe constant velocity joint 250, and the hub wheel 210 and the constantvelocity joint 250 are connected together in a torque-transmittingmanner through the two side splines 280 and 290 meshing with each other.

In order to interconnect the hub shaft 213 of the hub wheel 210 and theouter ring 260 of the constant velocity joint 250, an internally-threadportion 263 corresponding to an male-threaded portion 273 of anconnecting bolt 270 is formed in the end wall portion 261 of the outerring 260 of the constant velocity joint 250, while a center hole 214 forthe passage of a shank 272 of the connecting bolt 270 therethrough isformed through a center portion of the hub shaft 213.

The two side splines 280 and 290 are meshed with each other, and in thiscondition the shank 272 of the connecting bolt 270 is passed through thecenter hole 214 of the hub shaft 213 from the outside thereof, and themale-threaded portion 273 on this shank 272 is threaded into theinternally-threaded portion 263 of the end wall portion 261 of the outerring 260 to be fastened thereto, thereby coupling the hub shaft 213 ofthe hub wheel 210 and the outer ring 260 of the constant velocity joint250 together.

Each tooth top 283 of the side spline 280 on the end wall portion 261 ofthe outer ring 260 of the constant velocity joint 250, as well as eachbottom land 292 of the side spline 290 on the hub shaft 213, is disposedin a pane (vertical plane) perpendicular to a center axis of the hubshaft 213.

In the condition in which the hub shaft 213 of the hub wheel 210 and theouter ring 260 of the constant velocity joint 250 are connected togetherby tightening the connecting bolt 270, each tooth top 283 of the sidespline 280 contacts the corresponding bottom land 292 of the side spline290. Also, each bottom land 282 of the side spline 280 of the constantvelocity joint 250 and a corresponding tooth top 293 of the side spline290 of the hub shaft 213 are disposed out of contact with each other,with a clearance S′ formed therebetween.

In the wheel support bearing apparatus disclosed in JP-A-57-178903, itis rather difficult to interconnect the hub shaft 213 of the hub wheel210 and the outer ring 260 of the constant velocity joint 250 in alignedrelation to each other (that is, with their center axes coinciding witheach other), with the two side splines 280 and 290 meshing with eachother, by tightening the connecting bolt 270, and it is thought that thehub shaft 213 of the hub wheel 210 and the outer ring 260 of theconstant velocity joint 250 can be brought out of alignment with eachother (that is, their center axes become misaligned with each other).This misalignment causes vibration and an abnormal sound.

SUMMARY OF THE INVENTION

With the above problem in view, it is an object of this invention toprovide a wheel support apparatus in which muddy water or the like,intruding into the interior through a clearance between two side surfacesplines formed respectively on an end surface of a hub shaft of a hubwheel and an end surface of a side wall portion of a constant velocityjoint and meshing with each other, can be satisfactorily discharged ordrained to the exterior under the influence of a centrifugal force.

Another object of this invention is to provide a wheel support apparatusin which the area of non-contact portions of two side surface splinesformed respectively on a hub wheel and a constant velocity joint isreduced, and accordingly the area of contact between mating tooth flanksof the two side surface splines is increased, thereby decreasing acontact pressure and a shear stress of the tooth flanks.

Further another object of this invention is to provide a wheel supportbearing apparatus in which a hub shaft of a hub wheel and an outer ringof a constant velocity joint can be aligned with each other by meshingengagement of two side splines formed respectively on an end surface ofthe hub shaft and an end surface of the outer ring of the constantvelocity joint.

In order to achieve the above objects, the present invention providesthe following arrangements.

(1) A wheel support apparatus comprising:

a hub wheel which includes a hub shaft and is to mount a wheel thereon,a first side surface spline being formed on an end surface of the hubshaft; and

a constant velocity joint which includes an outer ring connected to thehub shaft in a torque-transmitting manner, a second side surface splinemeshed with the first side surface spline being formed on an end surfaceof a side wall portion of the outer ring abutting against the endsurface of the hub shaft,

wherein each of the first and second side surface splines includes anumber of spline teeth, and

wherein at least one of the spline teeth of at least one of the firstand second side surface splines is removed to form a removal portionwhich forms a drain passage.

(2) The wheel support apparatus according to (1), wherein

the hub shaft includes a bore and an interconnecting shaft whichconnects the hub shaft and the outer ring together and is passed throughthe bore, and

the bore is formed into a tapering hole, and has one end of a largerdiameter disposed close to the first side surface spline, and isgradually decreasing in diameter from the one end thereof toward theother end thereof.

(3) A wheel support apparatus comprising:

a hub wheel which includes a hub shaft and is to mount a wheel thereon,a first side surface spline being formed on an end surface of the hubshaft; and

a constant velocity joint which includes an outer ring connected to thehub shaft in a torque-transmitting manner, a second side surface splinemeshed with the first side surface spline being formed on an end surfaceof a side wall portion of the outer ring abutting against the endsurface of the hub shaft,

wherein each of the first and second side surface splines includes anumber of spline teeth and bottom lands defined between the splineteeth, and

wherein the bottom lands of at least one of the first and second sidesurface splines defines a circular inner periphery, a circular outerperiphery and a base circle lying generally midway between the circularinner and outer peripheries, and each of the bottom lands includes aradially-inner inclined surface which is defined between the circularinner periphery and the base circle and gradually increases in depthfrom the base circle toward the circular inner periphery and aradially-outer inclined surface which is defined between the circularouter periphery and the base circle and gradually increase in depth fromthe base circle toward the circular outer periphery, thereby each of thebottom lands is formed into a mountain-like shape in which the basecircle is formed as an apex.

(4) The wheel support apparatus according to (3), wherein at least oneof the spline teeth of at least one of the first and second side surfacesplines is removed to form a removal portion which forms a drainpassage.

(5) A wheel support apparatus comprising:

a hub wheel which includes a hub shaft and is to mount a wheel thereon,a first side surface spline being formed on an end surface of the hubshaft; and

a constant velocity joint which includes an outer ring connected to thehub shaft in a torque-transmitting manner, a second side surface splinemeshed with the first side surface spline being formed on an end surfaceof a side wall portion of the outer ring abutting against the endsurface of the hub shaft,

wherein each of the first and second side surface splines includes anumber of spline teeth and bottom lands defined between the splineteeth,

wherein the tooth tops of the spline teeth of one of the first andsecond side splines and the bottom lands of the other side surfacespline are formed into an arc-shaped surface disposed on a circle havinga center disposed on a center of pivotal movement of the constantvelocity joint, and

wherein the arc-shaped tooth tops contact the corresponding arc-shapedbottom lands so that the hub shaft and the outer ring can be alignedwith each other.

(6) The wheel support bearing apparatus according to (5), wherein an endportion of the hub shaft is caulked radially outwardly to form a caulkedportion to which an inner ring of a rolling bearing is fixed, and thefirst side spline is formed on an end surface of the caulked portion.(7) The wheel support apparatus according to (5), wherein at least oneof the spline teeth of at least one of the first and second side surfacesplines is removed to form a removal portion which forms a drainpassage.(8) A wheel support apparatus comprising:

a hub wheel which includes a hub shaft and is to mount a wheel thereon,a first side surface spline being formed on an end surface of the hubshaft; and

a constant velocity joint which includes an outer ring connected to thehub shaft in a torque-transmitting manner, a second side surface splinemeshed with the first side surface spline being formed on an end surfaceof a side wall portion of the outer ring abutting against the endsurface of the hub shaft,

wherein each of the first and second side surface splines includes anumber of spline teeth and bottom lands defined between the splineteeth,

wherein the tooth tops of the spline teeth of one of the two sidesplines and the bottom lands of the other side spline are formed into atapering surface inclined relative to a plane perpendicular to a centeraxis of the hub shaft, and

wherein the tapering tooth tops contact the corresponding taperingbottom lands so that the hub shaft and the outer ring can be alignedwith each other.

(9) The wheel support bearing apparatus according to (8), wherein an endportion of the hub shaft is caulked radially outwardly to form a caulkedportion to which an inner ring of a rolling bearing is fixed, and thefirst side spline is formed on an end surface of the caulked portion.(10) The wheel support apparatus according to (8), wherein at least oneof the spline teeth of at least one of the first and second side surfacesplines is removed to form a removal portion which forms a drainpassage.

With the arrangement of (1) and (2), during the travel of a vehicle(during the transmission of a torque), the torque of the outer ring ofthe constant velocity joint is transmitted to the hub shaft through thetwo side surface splines formed respectively on the end surface of theside wall portion of the outer ring and the end surface of the hubshaft, so that the wheel is rotated together with the hub wheel.

When muddy water or the like splashed up by the wheel intrudes into theinterior through a clearance between the two meshed side surface splinesduring the travel of the vehicle, this muddy water or the like is flowedtoward the outer peripheries of the two side surface splines under theinfluence of a centrifugal force, and is discharged (or drained) to theexterior through the drain passage formed by the removal portion (fromwhich the tooth is removed) of the side surface spline.

Thus, the muddy water or the like intruding into the interior through aclearance between the two side surface splines meshed with each othercan be satisfactorily discharged to the exterior through the drainpassage, and therefore the development of rust can be prevented.

With the arrangements of (3) and (4), for example, during the travel ofthe vehicle, a torque of the constant velocity joint is transmitted tothe hub wheel through the two side surface splines (formed respectivelyon the end surface of the hub shaft and the end surface of the outerring of the constant velocity joint) meshing with each other, so thatthe wheel is driven to be rotated.

Thus, the torque of the constant velocity joint can be satisfactorilytransmitted to the hub wheel through the two side surface splinesmeshing with each other, and therefore in contrast with the conventionalstructure, a relative slip between the end surface of the outer ring ofthe constant velocity joint and the end surface of the hub shaft of thehub wheel can be suppressed, thereby preventing the generation of anabnormal sound.

Furthermore, each bottom land of at least one of the two side surfacesplines has the mountain-like shape, and includes the radially-innerinclined surface, and the radially-outer inclined surface. Therefore, ascompared with the case where each bottom land of each of the sidesurface splines is formed into an inclined surface gradually increasingin depth from its radially-inner end toward its radially-outer end, thearea of non-contact portions of the two side surface splines can bereduced.

Namely, the meshing engagement of the two side surface splines can beprevented from being limited at the radially-inner portions of thebottom lands, and therefore the area of the non-contact portions of thetwo side surface splines can be reduced.

The area of the non-contact portions of the two side surface splines isthus reduced, and accordingly the area of contact between mating toothflanks of the two side surface splines can be increased, and a contactpressure and a shear stress of the tooth flanks can be reduced, so thatthe durability can be enhanced.

With the arrangement of (5), when the outer ring of the constantvelocity joint and the hub shaft are coupled together by tightening theconnecting bolt, with the two side splines (formed respectively on theouter ring and the hub shaft) meshing with each other, each tooth top ofthe one side spline and the corresponding bottom land of the other sidespline contact each other at their arc-shaped surfaces each disposed onthe circle having the center disposed on the axis of pivotal movement ofthe constant velocity joint. Thus, these arc-shaped surfaces contacteach other so that the hub shaft of the hub wheel and the outer ring ofthe constant velocity joint can be aligned with each other (that is,their center axes can coincide with each other), and therefore vibrationand an abnormal sound caused by misalignment can be prevented.

Furthermore, each tooth top of the one side spline and the correspondingbottom land of the other side spline contact each other at theirarc-shaped surfaces, and therefore the area of contact between themeshed side splines is larger as compared with the conventionalstructure of FIG. 19 in which the mating tooth top and bottom landcontact each other at their surfaces parallel to a plane perpendicularto the center axis of the hub shaft. Therefore, the torque-transmittingability is more excellent.

Furthermore, when a load is exerted so as to incline or pivotally movethe center axis of the hub shaft relative to the center axis of theouter ring of the constant velocity joint about the axis of pivotalmovement of the constant velocity joint, for example, during the travelof the vehicle, this load can be received by the relevant tooth tops(arc-shaped surfaces) and bottom lands (arc-shaped surfaces) of the twoside splines in such a manner that this load is distributed over theentire arc-shaped contact surfaces of the relevant tooth tops and bottomlands of the two side splines. Therefore, this load is prevented fromconcentrating on localized portions (outer peripheral portions) of thetwo side splines, and therefore the excellent durability can beobtained.

With the arrangement of (8), when the outer ring of the constantvelocity joint and the hub shaft are coupled together by tightening theconnecting bolt, with the two side splines (formed respectively on theouter ring and the hub shaft) meshing with each other, each tooth top ofthe one side spline and the corresponding bottom land of the other sidespline contact each other at their tapering surfaces.

Thus, each tapering tooth top of the one side spline and thecorresponding tapering bottom land of the other side spline contact eachother so that the hub shaft of the hub wheel and the outer ring of theconstant velocity joint can be aligned with each other (that is, theircenter axes can coincide with each other), and therefore vibration andan abnormal sound caused by misalignment can be prevented.

Furthermore, each tooth top and the corresponding bottom land of the twoside splines contact each other at their tapering surfaces, andtherefore the area of contact between the meshed side splines is largeras compared with the conventional structure in which the mating toothtop and bottom land contact each other at their surfaces parallel to aplane perpendicular to the center axis of the hub shaft. Therefore, thetorque-transmitting ability is more excellent.

With the arrangements of (6) and (9), the side spline is formed on theend surface of the caulked portion of the hub shaft of the hub wheel,and by doing so, the outer diameter of this side spline can be madelarger. Then, the side spline corresponding in outer diameter to theside spline of the hub shaft is formed on an end surface of an end wallportion of the outer ring of the constant velocity joint, and the twoside splines are meshed with each other, and with this construction thetorque-transmitting ability can be enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side cross-sectional view showing a first embodiment of awheel support apparatus of the present invention.

FIG. 2 is a developed view showing a condition in which two side surfacesplines formed respectively on an end surface of a hub shaft and an endsurface of a side wall portion of an outer ring of a constant velocityjoint are in mesh with each other.

FIG. 3 is a view explanatory of a modified form of the invention inwhich two of a number of teeth of the side surface spline which arespaced through an angle of approximately 180 degrees from each other areremoved.

FIG. 4 is a view explanatory of another modified form of the inventionin which three of a number of teeth of the side surface spline which arespaced through an angle of approximately 120 degrees from one anotherare removed.

FIG. 5 is a side cross-sectional view of a second embodiment of a wheelsupport apparatus of the invention.

FIG. 6 is a side cross-sectional view showing a wheel support apparatusaccording to a third embodiment of the present invention.

FIG. 7 is an enlarged perspective view showing a portion of a sidesurface spline formed on an end surface of a hub shaft of a hub wheel.

FIG. 8 is an enlarged cross-sectional view showing a condition in whichtwo side surface splines are separated from each other.

FIG. 9 is an enlarged cross-sectional view showing a condition in whichthe two side surface splines are meshed with each other.

FIG. 10 is an enlarged cross-sectional view showing a condition in whichtwo side surface splines employed in a wheel support apparatus accordingto a fourth embodiment of the invention are separated from each other.

FIG. 11 is an enlarged cross-sectional view showing a condition in whichthe two side surface splines are meshed with each other.

FIG. 12 is a longitudinal cross-sectional view showing a wheel supportbearing apparatus according to a fifth embodiment of the presentinvention.

FIG. 13 is an enlarged cross-sectional view showing a condition in whichtwo side splines are separated from each other.

FIG. 14 is an enlarged cross-sectional view showing a condition in whichthe two side splines are in mesh with each other.

FIG. 15 is an enlarged cross-sectional view showing a condition in whichtwo side splines employed in a wheel support bearing apparatus accordingto a sixth embodiment of the invention are separated from each other.

FIG. 16 is an enlarged cross-sectional view showing a condition in whichthe two side splines are in mesh with each other.

FIG. 17 is a side cross-sectional view of a conventional wheel supportapparatus, showing a condition in which a connecting shaft portion of aconstant velocity joint is spline-fitted in a bore of a hub shaft of ahub wheel.

FIG. 18 is a cross-sectional view showing a condition in which a sidesurface spline on an end surface of an outer ring of a constant velocityjoint is meshed with a side surface spline on an end surface of a hubshaft of a hub wheel of a reference example.

FIG. 19 is a longitudinal cross-sectional view of a another conventionalwheel support bearing apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described withreference to FIGS. 1 and 2.

FIG. 1 is a side cross-sectional view showing the first embodiment of awheel support apparatus of the invention. FIG. 2 is an enlargedperspective view showing a portion of a side surface spline formed on anend surface of a hub shaft of a hub wheel.

As shown in FIG. 1, the wheel support apparatus of this first embodimentcomprises the hub wheel 10, a double row angular contact ball bearing 20serving as a rolling bearing, and a constant velocity joint 50.

As shown in FIG. 1, the hub wheel 10 includes a cylindrical hub shaft13, and a flange 11 formed integrally on an outer peripheral surface ofthe hub shaft 13 and disposed adjacent to one end of this hub shaft 13.A plurality of hub bolts 12 are fixedly secured to the flange 11 bypress-fitting, and are arranged at a predetermined pitch in acircumferential direction, and these hub bolts 12 are used to mount awheel (not shown) on the flange 11, with a brake rotor (not shown)interposed the flange 11 and the wheel.

The double row angular contact ball bearing 20 is mounted on the outerperiphery of the hub shaft 13, and this ball bearing 20 comprises anouter ring 30, an inner ring 21, a row of balls 41, a row of balls 42,and cages 45 and 46.

In this first embodiment, the hub shaft 13 of an integral constructionincludes a larger-diameter shaft portion 15 disposed close to the flange11, and a smaller-diameter shaft portion 16 which is suitably smaller indiameter than the larger-diameter shaft portion 15 and is continuouswith the larger-diameter shaft portion 15 with a step portion formedtherebetween. A raceway surface 22 corresponding to one raceway surface31 of the outer ring 30 is formed on an outer peripheral surface of thelarger-diameter shaft portion 15.

A raceway surface 23 corresponding to the other raceway surface 32 ofthe outer ring 30 is formed on an outer peripheral surface of the innerring 21. After the inner ring 21 is fitted on an outer peripheralsurface of the smaller-diameter shaft portion 16 of the hub shaft 13, adistal end portion of the smaller-diameter shaft portion 16 is caulkedor deformed to form a caulked portion 17, and by doing so, the innerring 21 is fixed between the step portion and the caulked portion 17.

The row of balls 41 and the cage 45 holding these balls 41 are disposedbetween the raceway surface 31 of the outer ring 30 and the racewaysurface 22 of the hub shaft 13, and also the row of balls 42 and thecage 46 holding these balls 42 are disposed between the raceway surface32 of the outer ring 30 and the raceway surface 23 of the inner ring 21.

A fixing flange 35 is formed integrally on the outer peripheral surfaceof the outer ring 30, and is adapted to be mounted by bolts on avehicle-side member (a knuckle or a carrier) supported on a suspension(not shown) of a vehicle.

In this embodiment, a well-known constant velocity joint called a Rzeppatype or Birfield type is used as the constant velocity joint 50 as shownin FIG. 1. This constant velocity joint 50 comprises an inner ring 52mounted on one end portion of a drive shaft 51 for rotation therewith,an outer ring 60, and a row of balls 53 disposed between the inner andouter rings 52 and 60, and a cage 54 holding the row of balls 53.

An connecting bolt 70 for connecting the hub wheel 10 and the constantvelocity joint 50 together projects from a central portion of a sidewall portion 61 of the outer ring 60 of the constant velocity joint 50.

In this first embodiment, the connecting bolt 70 is separate from theouter ring 60 of the constant velocity joint 50, and has a head 71 and ashank 72. A through hole 63 is formed through the central portion of theside wall portion 61 of the outer ring 60 of the constant velocity joint50.

The shank 72 of the connecting bolt 70 is passed through the throughhole 63 (in the outer ring 60 of the constant velocity joint 50) from aninner open end thereof, and a larger-diameter portion 72 a defining aproximal end portion of the shank 72 is press-fitted into the throughhole 63 until a lower surface of the head 71 is brought into abuttingengagement with the inner surface of the side wall portion 61, and bydoing so, the connecting bolt 70 is fixed to the outer ring 60 of theconstant velocity joint 50 such that the shank 72 projects from the sidewall portion 61 of the outer ring 60. An male-threaded portion 73 isformed on a distal end portion of the shank 72 of the connecting bolt70, and a caulking groove 74 for preventing the rotation of a lock nut75 is formed in the male-threaded portion 73.

As shown in FIG. 1, a side surface spline 18 is formed on the endsurface of the hub shaft 13 of the hub wheel 10 (that is, on the endsurface of the caulked portion 17 of the hub shaft 13 in this firstembodiment), and a side surface spline 80 is formed on the end surfaceof the side wall portion 61 of the outer ring 60 (of the constantvelocity joint 50) abutting against the end surface of the hub shaft 13,and the two side surface splines 18 and 80 are meshed with each other toconnect the hub shaft 13 and the outer ring 60 of the constant velocityjoint 50 together in a torque-transmitting manner.

The hub wheel 10 and the constant velocity joint 50 are generallyunitarily coupled together so as to transmit a torque in the followingmanner.

Namely, first, the shank 72 of the interconnecting bolt 70 projectingfrom the end surface of the side wall portion 61 of the outer ring 60 ofthe constant velocity joint 50 is inserted into a bore 14 of the hubshaft 13 from one end thereof (that is, the inboard end in the directionof the width of the vehicle) toward the other end thereof (that is, theoutboard end in the width of the vehicle).

Then, the male-threaded portion 73 at the distal end portion of theshank 72 of the connecting bolt 70 is projected outwardly from the otherend of the bore 14 such that the side surface spline 80 on the endsurface of the hub shaft 13 is meshed with the side surface spline 90 onthe end surface of the side wall portion 61 of the outer ring 60 of theconstant velocity joint 50. In this condition, the lock nut 75 isfastened onto the male-threaded portion 73. Then, part of a thinned endportion 76 of the lock nut 75 is caulked or deformed into the caulkinggroove 74 in the male-threaded portion 73, thereby preventing therotation of the lock nut 75, and by doing so, the hub wheel 10 and theconstant velocity joint 50 are coupled together in a torque-transmittingmanner.

The side surface spline 18 formed on the end surface of the hub shaft 13includes a number of teeth (spline teeth) 18 a, and the side surfacespline 80 formed on the end surface of the side wall portion 61 of theouter ring 60 of the constant velocity joint 50 includes a number ofteeth (spline teeth) 80 a. At least one of the teeth 18 a, 80 a of atleast one of the two side surface splines 18 and 80 is removed to form aremoval portion 82 which forms a drain passage 83, as shown in FIG. 2.

In this first embodiment, one of the teeth 80 a of the side surfacespline 80 formed on the end surface of the outer ring 60 of the constantvelocity joint 50 is removed to form the removal portion 82 which formsthe drain passage 83.

The wheel support apparatus of this first embodiment has the aboveconstruction.

Therefore, for example, during the travel of the vehicle, a torque ofthe drive shaft 51 is transmitted sequentially to the inner ring 52, theballs 53 and the outer ring 60 of the constant velocity joint 50, sothat the outer ring 60 is rotated in the same direction as the directionof rotation of the drive shaft 51.

The torque transmitted to the constant velocity joint 50 is furthertransmitted to the hub wheel 10 through the two side surface splines 18and 80 (formed respectively on the end surface of the hub shaft 13 (thatis, the end surface of the caulked portion 17) and the end surface ofthe side wall portion 61 of the outer ring 60 of the constant velocityjoint 50) meshing with each other, so that the wheel is driven to berotated.

When muddy water or the like splashed up by the wheel intrudes into theinterior through a clearance between the two meshed side surface splines18 and 80 during the travel of the vehicle, this muddy water or the likeis flowed toward the outer peripheries of the side surface splines 18and 80 under the influence of a centrifugal force, and is discharged (ordrained) to the exterior through the drain passage 83 formed by theremoval portion 82 (from which the tooth 80 a is removed) of the sidesurface spline 80.

Thus, the muddy water or the like intruding into the interior through aclearance between the two side surface splines 18 and 80 meshed witheach other can be satisfactorily discharged to the exterior through thedrain passage 83, and therefore the development of rust can beprevented.

In the above first embodiment, one of the teeth 80 a of the side surfacespline 80 formed on the end surface of the side wall portion 61 of theouter ring 60 of the constant velocity joint 50 is removed to form theremoval portion 82 which forms the discharge passage 83. However, two ofthe teeth 80 a of the side surface spline 80 which are spaced through anangle of approximately 180 degrees from each other can be removed toform two removal portions 82 which form respective drain passages 83, asshown in FIG. 3. In another modified form of the invention, three of theteeth 80 a of the side surface spline 80 which are spaced through anangle of approximately 120 degrees from one another are removed to formthree removal portions 82 which form respective drain passages 83, asshown in FIG. 4.

Namely, the number of the teeth 80 a to be removed from the side surfacespline 80 can be suitably determined in so far as the transmission of atorque through the two meshed side surface splines 18 and 80 will not beadversely affected.

In the case where at least one of the teeth 18 a of the side surfacespline 18 formed on the end surface of the hub shaft 13 of the hub wheel10 is removed to form a removal portion which forms a drain passage,also, similar advantageous effects can be achieved.

Second Embodiment

Next, a second embodiment of the invention will be described withreference to FIG. 5.

FIG. 5 is a side cross-sectional view showing the second embodiment of awheel support apparatus of the invention.

As shown in FIG. 5, in this second embodiment, a bore 114 of a hub shaft13 of a hub wheel 10 is formed into a tapering hole, and has one end ofa larger diameter disposed close to a side surface spline 18, and isgradually decreasing in diameter from the one end thereof toward theother end thereof.

The other construction of this second embodiment is similar to that ofthe first embodiment, and therefore those portions of the secondembodiment identical in construction to the corresponding portions ofthe first embodiment are designated by identical reference numerals,respectively, and description thereof is omitted.

Therefore, in this second embodiment, also, when muddy water or the likesplashed up by the wheel intrudes into the interior through a clearancebetween two meshed side surface splines 18 and 80 during the travel ofthe vehicle, this muddy water or the like is flowed toward the outerperipheries of the side surface splines 18 and 80 under the influence ofa centrifugal force, and is discharged (or drained) to the exteriorthrough a drain passage 83 formed by a removal portion 82 (from which atooth 80 a is removed) of the side surface spline 80.

Particularly in this second embodiment, the muddy water or the like,intruding into the one end portion of the bore (tapering hole) 114 ofthe hub shaft 13 through a clearance between the two side surfacesplines 18 and 80 meshed with each other, is restrained from flowingtoward the other end of the bore 114, and therefore the draining abilitycan be enhanced.

Third Embodiment

A third embodiment of the present invention will be described withreference to FIGS. 6 to 9.

FIG. 6 is a side cross-sectional view showing a wheel support apparatusaccording to the third embodiment of the invention. FIG. 7 is anenlarged perspective view showing a portion of a side surface splineformed on an end surface of a hub shaft of a hub wheel. FIG. 8 is anenlarged cross-sectional view showing a condition in which two sidesurface splines are separated from each other. FIG. 9 is an enlargedcross-sectional view showing a condition in which the two side surfacesplines are meshed with each other.

In the third embodiment of the invention, those portions similar inconstruction to the corresponding portions of the first embodiment willbe designated by identical reference numerals, respectively, andexplanation thereof will be omitted.

As shown in FIGS. 6 and 7, a side surface spline 380 is formed on theend surface of the hub shaft 13 of the hub wheel 10 (that is, on the endsurface of the caulked portion 17 of the hub shaft 13 in this thirdembodiment), and a side surface spline 490 is formed on the end surfaceof the side wall portion 61 of the outer ring 60 (of the constantvelocity joint 50) abutting against the end surface of the hub shaft 13,and the two side surface splines 380 and 390 are meshed with each otherto connect the hub shaft 13 and the outer ring 60 of the constantvelocity joint 50 together in a torque-transmitting manner.

As shown in FIGS. 7 and 8, each of bottom lands 382 of spline teeth 381of the side surface spline 380 formed on the end surface of the caulkedportion 17 of the hub shaft 13 is formed into a mountain-like shape, andhas an apex 83 disposed on a base circle (having a diameter C) lyinggenerally midway between (that is, lying generally in the middle of thedistance between) a circular inner periphery (having a diameter A) ofthe caulked portion 17 of the hub shaft 13 and a circular outerperiphery (having a diameter B) thereof, and includes a radially-innerinclined surface 384 gradually increasing in depth from the apex 383toward a radially-inner end thereof, and a radially-outer inclinedsurface 385 gradually increasing in depth from the apex 383 toward aradially-outer end thereof.

In this third embodiment, here, a center axis of the caulked portion 17is represented by L, and a reference line disposed perpendicularly tothe center axis L and extending on and along a tooth top 386 of thespline tooth 381 of the side surface spline 380 is represented by H, anda point of intersection of the center axis L and the reference line H isrepresented by O1, and a point of intersection of the reference line Hand a circle having a diameter D twice larger than the diameter C of thebase circle is represented by O2. Then, the radially-outer inclinedsurfaces 385 are disposed on a conical surface passing through theintersection point O1 and inclined at an angle θ1 relative to thereference line H.

The apex 383 is disposed at a point of intersection of the above conicalsurface (passing through the intersection point O1 and inclined at theangle θ1 relative to the reference line H) and the base circle (havingthe diameter C). The radially-inner inclined surfaces 384 are disposedon a conical surface passing through the intersection point O2 andinclined at an angle θ2 (which is equal to the angle θ1) relative to thereference line H.

On the other hand, each of bottom lands 392 of spline teeth 391 of theside surface spline 390 formed on the end surface of the side wallportion 61 of the outer ring 60 of the constant velocity joint 50 isalso formed into a mountain-like shape as described above for the sidesurface spline 380 on the hub shaft 13, and each bottom land 392includes a radially-inner inclined surface 394 gradually increasing indepth from an apex 393 toward a circular inner periphery of the sidewall portion 61, and a radially-outer inclined surface 395 graduallyincreasing in depth from the apex 393 toward a circular outer peripheryof the side wall portion 61.

The hub wheel 10 and the constant velocity joint 50 are generallyunitarily coupled together so as to transmit a torque in the followingmanner.

Namely, first, the shank 72 of the connecting bolt 70 projecting fromthe end surface of the side wall portion 61 of the outer ring 60 of theconstant velocity joint 50 is inserted into a bore 14 of the hub shaft13 from one end thereof (that is, the inboard end in the direction ofthe width of the vehicle) toward the other end thereof (that is, theoutboard end in the width of the vehicle).

Then, the male-threaded portion 73 at the distal end portion of theshank 72 of the connecting bolt 70 is projected outwardly from the otherend of the bore 14 such that the side surface spline 380 on the endsurface of the hub shaft 13 is meshed with the side surface spline 390on the end surface of the side wall portion 61 of the outer ring 60 ofthe constant velocity joint 50. In this condition, the lock nut 75 isfastened onto the male-threaded portion 73. Then, part of a thinned endportion 76 of the lock nut 75 is caulked or deformed into the caulkinggroove 74 in the male-threaded portion 73, thereby preventing therotation of the lock nut 75, and by doing so, the hub wheel 10 and theconstant velocity joint 50 are coupled together in a torque-transmittingmanner (see FIG. 6).

The wheel support apparatus of this third embodiment has the aboveconstruction.

Therefore, for example, during the travel of the vehicle, a torque ofthe drive shaft 51 is transmitted sequentially to the inner ring 52, theballs 53 and the outer ring 60 of the constant velocity joint 50, sothat the outer ring 60 is rotated in the same direction as the directionof rotation of the drive shaft 51.

The torque thus transmitted to the constant velocity joint 50 is furthertransmitted to the hub wheel 10 through the two side surface splines 380and 390 (formed respectively on the end surface of the hub shaft 13 andthe end surface of the outer ring 60 of the constant velocity joint 50)meshing with each other, so that the wheel is driven to be rotated.

As described above, the torque can be satisfactorily transmitted fromthe constant velocity joint 50 to the hub wheel 10 through the two sidesurface splines 380 and 390 meshing with each other.

Therefore, in contrast with the conventional structure, a relative slipbetween the end surface of the outer ring 60 of the constant velocityjoint 50 and the end surface of the hub shaft 13 (that is, the endsurface of the caulked portion 17) of the hub wheel 10 can besatisfactorily suppressed. Therefore, the generation of an abnormalsound due to a relative slip between the end surface of the outer ring60 of the constant velocity joint 50 and the end surface of the hubshaft 13 of the hub wheel 10 can be prevented.

Furthermore, each bottom land 382, 392 of each of the two side surfacesplines 380, 390 has the mountain-like shape, and includes theradially-inner inclined surface 384, 394, and the radially-outerinclined surface 385, 395. Therefore, as compared with the case whereeach bottom land of each of the two side surface splines is formed intoan inclined surface gradually increasing in depth from itsradially-inner end toward its radially-outer end, the area ofnon-contact portions of the two side surface splines 380 and 390 can bereduced.

Namely, the radially-inner inclined surface 384, 394 is formed at eachbottom land 382, 392 of each of the two side surface splines 380, 390,and by doing so, the meshing engagement of the two side surface splines380 and 390 can be prevented from being limited at the radially-innerportions of the bottom lands 382, 392. Therefore, the area of thenon-contact portions of the two side surface splines 380, 390 can bereduced.

The area of the non-contact portions of the two side surface splines380, 390 is thus reduced, and accordingly the area of contact betweentooth flanks of the mating spline teeth of the two side surface splines380, 390 can be increased, and a contact pressure and a shear stress ofthe tooth flanks can be reduced, so that the durability can be enhanced.

Fourth Embodiment

Next, a fourth embodiment of the invention will be described withreference to FIGS. 10 and 11.

FIG. 10 is an enlarged cross-sectional view showing a condition in whichtwo side surface splines employed in a wheel support apparatus accordingto a fourth embodiment of the invention are separated from each other.FIG. 11 is an enlarged cross-sectional view showing a condition in whichthe two side surface splines are meshed with each other.

As shown in FIGS. 10 and 11, in this fourth embodiment, a tooth top 396(or 386) of each spline tooth 391 (or 381) of one (390 (or 380)) of thetwo side surface splines 380, 390 is formed into a shape correspondingor conforming to a shape of each bottom land 382 (or 392) of the otherside surface spline 380 (or 390).

Namely, as shown in FIG. 10, the tooth top 396 of each spline tooth 391of the side surface spline 390 formed on an end surface of an outer ring60 of a constant velocity joint 50 is formed into a V-shape, and has avalley portion 397 opposed to an apex 383 of the bottom land 382 of thespline tooth 381 of the side surface spline 380 formed on an end surfaceof a hub shaft 13, and includes a radially-inner tooth top portion 398gradually increasing in height from the valley portion 397 toward aradially-inner end thereof, and a radially-outer tooth top portion 399gradually increasing in height from the valley portion 397 toward aradially-outer end thereof.

The other construction of this fourth embodiment is similar to that ofthe third embodiment, and therefore those portions of the fourthembodiment identical in construction to the corresponding portions ofthe third embodiments are designated by identical reference numerals,respectively, and description thereof is omitted.

In the wheel support apparatus of this fourth embodiment having theabove construction, the tooth top 396 of each spline tooth 391 of theone side surface spline 390 is formed into the V-shape corresponding tothe mountain-like shape of the bottom land 382 of the other side surfacespline 380. With this construction, the area of non-contact portions ofthe two side surface splines 380, 390 can be further reduced, andaccordingly the area of contact between mating tooth flanks of the twoside surface splines 380, 390 can be increased. Therefore, a contactpressure and a shear stress of the tooth flanks can be effectivelyreduced.

The present invention is not limited to the above third and fourthembodiments.

For example, in the above third and fourth embodiments, each bottom land382, 392 of each of the two side surface splines 380, 390 is formed intothe mountain-like shape, and has the radially-inner inclined surface384, 394 and the radially-outer inclined surface 385, 395. However, eachbottom land 82 or 92 of one of the two side surface splines 380, 390 maybe formed into the mountain-like shape, and has the radially-innerinclined surface 384 or 394 and the radially-outer inclined surface 385or 395, and in this case, also, the advantageous effects of the presentinvention can be achieved.

Furthermore, in the above third embodiment, the connecting bolt 70separate from the outer ring 60 of the constant velocity joint 50 ispress-fitted into the through hole 63 of the side wall portion 61 of theouter ring 60, and is fixed to the outer ring 60. However, an connectingbolt portion may be formed integrally with and extending from the sidewall portion 61 of the outer ring 60, and in this case, also, theadvantageous effects of the invention can be achieved.

Furthermore, instead of the double row angular contact ball bearing 20serving as the rolling bearing of the hub wheel, a double row taperedroller bearing can be used, and in this case, also, the advantageouseffects of the invention can be achieved.

Fifth Embodiment

A fifth embodiment of the present invention will be describedhereinafter with reference to FIGS. 12 to 14.

FIG. 12 is a longitudinal cross-sectional view showing a wheel supportbearing apparatus according to a fifth embodiment of the presentinvention. FIG. 13 is an enlarged cross-sectional view showing acondition in which two side splines are separated from each other. FIG.14 is an enlarged cross-sectional view showing a condition in which thetwo side splines are in mesh with each other.

In the fifth embodiment of the invention, those portions similar inconstruction to the corresponding portions of the first embodiment willbe designated by identical reference numerals, respectively, andexplanation thereof will be omitted.

As shown in FIGS. 12 and 13, a side surface spline 480 is formed on theend surface of the hub shaft 13 of the hub wheel 10 (that is, on the endsurface of the caulked portion 17 of the hub shaft 13 in this fifthembodiment), and a side surface spline 490 is formed on the end surfaceof the side wall portion 61 of the outer ring 60 (of the constantvelocity joint 50) abutting against the end surface of the hub shaft 13,and the two side surface splines 480 and 490 are meshed with each otherto connect the hub shaft 13 and the outer ring 60 of the constantvelocity joint 50 together in a torque-transmitting manner.

As shown in FIGS. 13 and 14, each tooth top of one of the two sidesplines 480 and 490, as well as each bottom land of the other sidespline, is formed into an arc-shaped surface disposed on a circle havinga center disposed on a center of pivotal movement (or swinging movement)of the constant velocity joint 50.

In this fifth embodiment, the tooth top 493 of each spline tooth 491 ofthe side spline 490 of the constant velocity joint 50, as well as thebottom land 482 of each spline tooth 481 of the side spline 480 of thehub shaft 13, is formed into the arc-shaped surface disposed on thecircle which has a radius R and has the center O disposed on the centerof pivotal movement of the constant velocity joint 50.

A bottom land 492 of each spline tooth 491 of the side spline 490 of theconstant velocity joint 50 is disposed on a plane (vertical plane)perpendicular to a center axis of the outer ring 60 of the constantvelocity joint 50, and also a tooth top 483 of each spline tooth 481 ofthe side spline 480 of the hub shaft 13 is disposed on a plane (verticalplane) perpendicular to a center axis of the hub shaft 13 which iscoaxial with the center axis of the outer ring 60.

In the condition in which the hub wheel 10 and the constant velocityjoint 50 are connected together by fastening the lock nut 75 to theconnecting bolt 70 as shown in FIG. 14, each arc-shaped tooth top 493contacts the corresponding arc-shaped bottom land 482 so that the hubshaft 13 and the outer ring 60 of the constant velocity joint 50 can bealigned with each other, whereas each bottom land 492 and thecorresponding tooth top 483 disposed respectively on the vertical planesare held out of contact with each other, with a clearance S1 formedtherebetween.

In the wheel support bearing apparatus of this fifth embodiment havingthe above construction, when the hub wheel 10 and the constant velocityjoint 50 are to be generally unitarily connected together in atorque-transmitting manner, first, the shank 72 of the connecting bolt70 projecting from the end surface of the end wall portion 61 of theouter ring 60 of the constant velocity joint 50 is inserted into acentral hole (or bore) 14 of the hub shaft 13 from one end thereof (thatis, the inboard end in the direction of the width of the vehicle) towardthe other end thereof (that is, the outboard end in the width of thevehicle).

Then, the male-threaded portion 73 at the distal end portion of theshank 72 of the connecting bolt 70 is projected outwardly from the otherend of the central hole 14 such that the side spline 480 on the endsurface of the hub shaft 13 is meshed with the side spline 490 on theend surface of the outer ring 60 of the constant velocity joint 50.

In this condition, the lock nut 75 is fastened onto the male-threadedportion 73 of the connecting bolt 70. By thus fastening the lock nut 75onto the connecting bolt 70, the arc-shaped tooth top 493 of each splinetooth 491 of the side spline 490 contacts the arc-shaped bottom land 482of the corresponding spline tooth 481 of the side spline 480, so thatthe hub shaft 13 and the outer ring 60 of the constant velocity joint 50are aligned with each other.

Finally, part of a thinned end portion 76 of the lock nut 75 is caulkedor deformed into the caulking groove 74 in the male-threaded portion 73,thereby preventing the rotation of the lock nut 75, and by doing so, thehub wheel 10 and the constant velocity joint 50 are coupled together ina torque-transmitting manner (see FIG. 12).

As described above, the arc-shaped tooth top 493 of each spline tooth491 of the side spline 490 contacts the arc-shaped bottom land 482 ofthe corresponding spline tooth 481 of the side spline 480 so that thehub shaft 13 and the outer ring 60 of the constant velocity joint 50 canbe aligned with each other (that is, their center axes can coincide witheach other), and therefore vibration and an abnormal sound caused bymisalignment can be prevented.

Furthermore, the tooth top 493 of each spline tooth 491 of the sidespline 490 and the bottom land 82 of the corresponding spline tooth 481of the side spline 480 contact each other at their arc-shaped surfaces,and therefore the area of contact between the meshed side splines islarger as compared with the conventional structure of FIG. 19 in whichthe mating tooth top and bottom land contact each other at theirsurfaces parallel to a plane perpendicular to the center axis of the hubshaft. Therefore, the torque-transmitting ability is more excellent.

Furthermore, when a load is exerted so as to incline or pivotally movethe center axis of the hub shaft 13 relative to the center axis of theouter ring 60 of the constant velocity joint 50 about the axis ofpivotal movement of the constant velocity joint 50 (which coincides withthe center O), for example, during the travel of the vehicle, this loadcan be received by the tooth top (arc-shaped surface) 493 of eachrelevant spline tooth 491 of the side spline 490 and the bottom land(arc-shaped surface) 482 of the corresponding spline tooth 481 of theside spline 480 in such a manner that this load is distributed over theentire arc-shaped contact surfaces of the relevant tooth tops 493 andbottom lands 482. Therefore, this load is prevented from concentratingon localized portions (outer peripheral portions) of the spline teeth481 and 491 of the two side splines 480 and 490, and therefore theexcellent durability can be obtained.

Furthermore, in this fifth embodiment, the side spline 480 is formed onthe end surface of the caulked portion 17 formed by caulking ordeforming the end portion of the hub shaft 13 radially outwardly.Therefore, the outer diameter of the side spline 480 formed on thiscaulked portion 17 can be made larger as compared with the case wheresuch a caulked portion is not formed on the hub shaft 13. Then, the sidespline 490 corresponding in outer diameter to the side spline 480 of thehub shaft 13 is formed on the end surface of the end wall portion 61 ofthe outer ring 60 of the constant velocity joint 50, and is meshed withthe side spline 480, and with this construction the torque-transmittingability can be enhanced.

Sixth Embodiment

Next, a sixth embodiment of the invention will be described withreference to FIGS. 15 and 16.

FIG. 15 is an enlarged cross-sectional view showing a condition in whichtwo side splines employed in the sixth embodiment of a wheel supportbearing apparatus of the invention are separated from each other. FIG.16 is an enlarged cross-sectional view showing a condition in which thetwo side splines are in mesh with each other.

As shown in FIGS. 15 and 16, in this sixth embodiment, a side spline 180is formed on an end surface of a hub shaft 13 (that is, an end surfaceof a caulked portion 17) of a hub wheel 10, and a side spline 190 isformed on an end surface of an end wall portion 61 of a constantvelocity joint 50 which abuts against the end surface of the hub shaft13. A tooth top 193 of each spline tooth 191 of the side spline 190 ofthe constant velocity joint 50, as well as a bottom land 182 of eachspline tooth 181 of the side spline 180 of the hub shaft 13, is formedinto a tapering surface (or inclined surface) inclined relative to aplane perpendicular to a center axis of the hub shaft 13. Further, thetooth top 193 of each spline tooth 191 of the side spline 190 is formedinto the tapering surface gradually increasing in height from itsradially-outer end to its radially-inner end.

On the other hand, the bottom land 182 of each spline tooth 181 of theside spline 180 is formed into the tapering surface gradually increasingin depth from its radially-outer end to its radially-inner end.

A bottom land 192 of each spline tooth 191 of the side spline 190 of theconstant velocity joint 50 is disposed on a plane (vertical plane)perpendicular to a center axis of the outer ring 60 of the constantvelocity joint 50, and also a tooth top 183 of each spline tooth 181 ofthe side spline 180 of the hub shaft 13 is disposed on a plane (verticalplane) perpendicular to the center axis of the hub shaft 13 which iscoaxial with the center axis of the outer ring 60.

In a condition in which the hub wheel 10 and the constant velocity joint50 are connected together by fastening a lock nut (not shown in FIG. 16)to an connecting bolt 70 as shown in FIG. 16, each tapering tooth top193 contacts the corresponding tapering bottom land 182 so that the hubshaft 13 and the outer ring 60 of the constant velocity joint 50 can bealigned with each other, whereas each bottom land 192 and thecorresponding tooth top 183 disposed respectively on the vertical planesare held out of contact with each other, with a clearance S2 formedtherebetween.

The other construction of this sixth embodiment is similar to that ofthe fifth embodiment, and therefore those portions of the secondembodiment identical in construction to the corresponding portions ofthe fifth embodiment are designated by identical reference numerals,respectively, and description thereof is omitted.

Therefore, in the wheel support bearing apparatus of this sixthembodiment, the tapering tooth top 193 of each spline tooth 191 of theside spline 190 contacts the tapering bottom land 182 of thecorresponding spline tooth 181 of the side spline 180 so that the hubshaft 13 and the outer ring 60 of the constant velocity joint 50 can bealigned with each other (that is, their center axes can coincide witheach other), and therefore vibration and an abnormal sound caused bymisalignment can be prevented. Furthermore, the tooth top 193 of eachspline tooth 191 of the side spline 190 and the bottom land 182 of thecorresponding spline tooth 181 of the side spline 180 contact each otherat their tapering surfaces, and therefore the area of contact betweenthe meshed side splines is larger as compared with the conventionalstructure of FIG. 19 in which the mating tooth top and bottom landcontact each other at their surfaces parallel to a plane perpendicularto the center axis of the hub shaft. Therefore, the torque-transmittingability is more excellent.

In this sixth embodiment, also, the side spline 180 is formed on the endsurface of the caulked portion 17 formed by caulking or deforming theend portion of the hub shaft 13 radially outwardly, as described abovefor the fifth embodiment. Therefore, the outer diameter of the sidespline 180 formed on this caulked portion 17 can be made larger ascompared with the case where such a caulked portion is not formed on thehub shaft 13. Then, the side spline 190 corresponding in outer diameterto the side spline 180 of the hub shaft 13 is formed on the end surfaceof the end wall portion 61 of the outer ring 60 of the constant velocityjoint 50, and is meshed with the side spline 180, and with thisconstruction the torque-transmitting ability can be enhanced.

The present invention is not limited to the above first to sixthembodiments.

For example, in the above first to sixth embodiments, the connectingbolt 70 separate from the outer ring 60 of the constant velocity joint50 is press-fitted into the through hole 63 of the end wall portion 61of the outer ring 60, and is fixed to the outer ring 60. However, anconnecting bolt portion may be formed integrally with and extending fromthe end wall portion 61 of the outer ring 60, and in this case, also,the advantageous effects of the invention can be achieved.

Furthermore, there can be adopted a construction in which aninternally-threaded portion is formed in the end wall portion 61 of theouter ring 60 of the constant velocity joint 50, and an connecting boltis passed through a center hole of the hub shaft from the outboard sidein the direction of the width of the vehicle, and an male-threadedportion of this connecting bolt is threaded into the internally-threadedportion in the end wall portion 61 of the outer ring 60 of the constantvelocity joint 50. In this case, also, the advantageous effects of theinvention can be achieved.

Furthermore, instead of the double row angular contact ball bearing 20serving as the rolling bearing of the hub wheel, a double row taperedroller bearing can be used, and in this case, also, the advantageouseffects of the invention can be achieved.

Furthermore, the above embodiments may be combined each other. Forexample, the drain passage formed by removing the tooth of the splineaccording to the embodiment 1 may be formed in the wheel supportapparatus according to the third to sixth embodiments.

1. A wheel support apparatus comprising: a hub wheel which includes ahub shaft and is to mount a wheel thereon, a first side surface splinebeing formed on an end surface of the hub shaft; and a constant velocityjoint which includes an outer ring connected to the hub shaft in atorque-transmitting manner, a second side surface spline meshed with thefirst side surface spline being formed on an end surface of a side wallportion of the outer ring abutting against the end surface of the hubshaft, wherein each of the first and second side surface splinesincludes a number of spline teeth and bottom lands defined between thespline teeth, wherein the tooth tops of the spline teeth of one of thetwo side splines and the bottom lands of the other side spline areformed into a tapering surface inclined relative to a planeperpendicular to a center axis of the hub shaft, wherein the taperingtooth tops contact the corresponding tapering bottom lands so that thehub shaft and the outer ring can be aligned with each other, and whereinat least one of the spline teeth of at least one of the first and secondside surface splines is removed to form a removal portion which forms adrain passage.
 2. A wheel support apparatus comprising: a hub wheelwhich includes a hub shaft and is configured so as to mount a wheelthereon, a first side surface spline being formed on an end surface ofthe hub shaft; and a constant velocity joint which includes an outerring connected to the hub shaft in a torque-transmitting manner, asecond side surface spline meshed with the first side surface splinebeing formed on an end surface of a side wall portion of the outer ringabutting against the end surface of the hub shaft, wherein each of thefirst and second side surface splines includes a number of spline teethand bottom lands defined between the spline teeth, wherein the toothtops of the spline teeth of one of the two side splines and the bottomlands of the other side spline are formed into a tapering surfaceinclined relative to a plane perpendicular to a center axis of the hubshaft, wherein the tapering tooth tops contact the correspondingtapering bottom lands so that the hub shaft and the outer ring can bealigned with each other, wherein an end portion of the hub shaft iscaulked radially outwardly to form a caulked portion to which an innerring of a rolling bearing is fixed, and the first side spline is formedon an end surface of the caulked portion, wherein the end surface of thecaulked portion of the hub wheel extends on the plane substantiallyperpendicular to the center axis of the hub shaft, and wherein the endsurface of the side wall portion of the constant velocity joint extendson the plane substantially perpendicular to the center axis of the hubshaft.
 3. The wheel support apparatus according to claim 2, wherein aportion of at least one of the spline teeth of at least one of the firstand second side surface splines is removed to form a removal portionwhich forms a drain passage.
 4. The wheel support apparatus according toclaim 2, wherein at least one of the first and second side surfacesplines extends in a direction substantially perpendicular to an axisabout which the hub shaft rotates.
 5. The wheel support apparatusaccording to claim 2, wherein the caulked portion comprises an end faceof the hub shaft.
 6. The wheel support apparatus according to claim 2,wherein at least one of the spline teeth of at least one of the firstand second side surface splines are absent so as to form a drainpassage.
 7. The wheel support apparatus according to claim 2, whereinthe hub shaft includes a tapered bore.
 8. The wheel support apparatusaccording to claim 2, wherein the tooth tops of the spline teeth of another of the two side splines and the bottom lands of the other sidespline plane perpendicular to the center axis of the hub shaft.
 9. Thewheel support apparatus according to claim 2, wherein the tooth tops ofthe spline teeth of an other of the two side splines and the bottomlands of an other side spline are inclined at an angle different fromthe an angle of the tapered surface of the tooth tops of the splineteeth of the one of the two side splines and the bottom lands of theother side spline one of the two side splines.